Ball raceway float control devices typically include an enclosed tubular raceway and a ball which travels through the raceway to actuate a switch associated with the raceway. Ball raceway and switch assemblies can therefore respond to changes in attitude to control electrical circuits in power devices.
Ball raceway switch devices may be employed as a component of a sealed float control unit to control various means such as sump pumps, valves, etc. The float control unit may change attitude as the level of liquid varies, such as in sump where the level of water varies between a first lower level and a second higher level which is sufficient to activate a sump pump. When the water level is low, the ball raceway and switch assembly is typically disposed in a downwardly facing position such that the ball is positioned in an outside first end of the raceway. As the water level rises, the control unit floats to a higher attitude and the ball rolls to the opposite second end of the raceway to close a switch to actuate the pump. As the pump evacuates the water, the float returns to the original downwardly sloping attitude and the ball returns to the outside first end of the raceway to open the switch and shut off the motor. (Such motors being capable of activating various means, i.e., pumps, valves, etc.) Examples of various types of devices are disclosed in U.S. Pat. Nos. 3,944,770; 4,021,145; and 4,629,841.
The latter example, namely, U.S. Pat. No. 4,629,841, issued to Riback et al, assigned to the common assignee of the present invention, is an attitude controlled float switch which includes a ball cage for actuating a mechanical switch. The ball cage is free to pivot between either of two operative positions in response to a ball rolling from one end of the raceway, through the cage, and then to the other end of the raceway. The ball cage is retained in one of two operative positions by an over center spring. An alleged safety arm is provided to prevent the cage from inadvertently changing to another position so as to prevent entrapment of the ball between the cage an end of the raceway. The ballcage employed in Riback '841 attempted to enable the ball and ballcage to retain synchronism to operate a miniature switch in response to changes in attitude of the ball raceway float switch.
However, a difficulty surfaced in the use of the Riback device, namely, the ballcage may undesirably change position without movement of the ball therethrough as a result of vibrations, or inversion of the shipping container, such as may be incurred during shipment. This change in position of the ball cage can cause the ball to become entrapped between the ball cage and an end portion of the raceway with the result that the float switch may not be able to function properly, i.e., the switch may not be activatable, whereby the motor will not start, or, alternatively the motor may run continuously and be subject to burnout.
Similarly, mechanical switches employed in devices such as the Riback device set forth above, although generally reliable, tend to be subject to wear, fatigue, and potential malfunction. Alternative forms might be desirable.